A conventional spanner which minimizes the operational angle of helical movement for tightening or loosening a bolt, nut, or the like, is disclosed in unexamined Japanese Utility Model Publication No. Hei 3-33066 (hereinafter referred to as `the Japanese publication`).
The spanner of the Japanese publication (not shown) includes the following: a lever handle; an exterior ring connected to an end of the lever handle; an interior ring coaxially disposed in the exterior ring; a plurality of columned cams each having a non-circular cross section which is retained at regular intervals in an annular space formed between an outer peripheral surface of the interior ring and an inner peripheral surface of the exterior ring; and an annular spring wherein the annular spring is mounted, urged to enlarging in diameter, in recess grooves each formed in the columned cam, such that each columned cam is rolled on the outer peripheral surface of the interior ring and wedged non-circular surface of each columned cam into the inner peripheral surface of the exterior ring.
However, the conventional spanner has problems when the space around a bolt head, nut, or the like is too narrow to insert the bolt, nut, etc. in an engaging bore of the interior ring, or when the rotational movement of the lever handle is difficult. In such cases, the helical movement by using the conventional spanner for tightening or loosening the bolt nut or the like is impossible